THE leader of the Scottish Conservatives is to argue that the benefit of the single UK market is a positive reason to remain part of the Union.

The absence of barriers to trade helped Scotland become more successful and more prosperous, Ruth Davidson will tell members of the Conservative Friends of the Union campaign in Edinburgh today.

But Ms Davidson's intervention was described by a spokesman for First Minister Alex Salmond as being "riddled with bogus and redundant arguments".

An independent Scotland will remain part of the European Union, with freedom of goods and services, the spokesman said.

The Conservative leader will point out that Scotland exports twice as much to England as to any other part of the world, with trade in the rest of the UK increasing by more than 60 per cent in a decade.

"If we were to leave the United Kingdom it would inevitably mean one set of rules and regulations in Scotland and another set just across the border in the remainder of the UK," she will say.

"Different financial regulations, different employment laws, different insurance requirements, different tax authorities, different accreditations and qualifications with which small companies would be obliged to contend - all barriers to trade, obstructions to economic growth and impediments to the job creation in Scotland we all want to see."

The Better Together parties, which include the Conservatives, Labour and the Liberal Democrats, have been accused by independence campaigners of failing to find a positive message in their campaign.

The industry supports more than 160,000 jobs and accounts for £9.9 billion of business conducted with the rest of the UK, and about 84% of mortgages sold by Scottish firms were to people in the rest of the UK, she argues.

Referring to earlier research published by the UK Government, she says Scottish firms sold 19,075 pension products to Scottish households last year and over the same period sold 186,627 across the rest of the UK.

"I think that puts matters firmly in perspective," she will say.

"A sixth of a million Scottish jobs, nearly £10 billion of financial service exports, and most of that built on doing business within the single UK market.

"The facts are clear: Scotland is more successful and more prosperous by working in partnership with the rest of the three nations in the UK."

A spokesman for the First Minister said: "It has been a bad summer from the No campaign as their scare stories have rebounded on them and they have lost support.

"An independent Scotland will mean decisions taken here in Scotland, and that we always get the governments we vote for - and more and more people are now turning to a Yes vote as they hear the arguments laid out before them.

"Ruth Davidson's latest feeble contribution to the No camp's self-styled Project Fear is riddled with bogus and redundant arguments.

"An independent Scotland will remain part of the European Union, which means access to a single market of around half a billion people and complete freedom of goods, services and people across Europe.

"The only threat to EU membership - and all of the jobs, investment and prosperity that brings - is the attempt by Ruth Davidson's Tory colleagues at Westminster to stage an in-out referendum of EU membership.

"A Yes vote in next year's referendum will mean Scotland does not face the prospect of being dragged to the exit door of Europe against its will."